US EPA to regulate emissions from large nonroad SI engines

20 September 2001

On September 14, the US EPA has signed a Notice of Proposed Rulemaking: Control of Emissions from Nonroad Large Spark Ignition Engines and Recreational Engines (Marine and Land-based). The proposal presents regulatory strategies for new nonroad vehicles and engines that are not yet regulated under the existing EPA’s nonroad engine programs. The proposal covers the following engines:

Recreational vehicles: Land-based spark-ignition recreational engines, including those used in snowmobiles, off-highway motorcycles, and all-terrain vehicles.

Large SI engines: Land-based spark-ignition engines rated over 19 kW, including engines used in forklifts, generators, airport tugs, and various farm, construction, and industrial equipment. This category also includes auxiliary marine engines, but does not include engines used in recreational vehicles.

Recreational marine diesel engines.

With regard to Large SI engines, the EPA is proposing a two-phase program. The first phase of the standards, to go into effect in 2004, are the same as those adopted in 1998 by the California Air Resources Board. These standards will reduce combined HC and NOx emissions by nearly 75%, based on a steady-state test. In 2007, the EPA proposes to supplement these standards by setting limits that would require optimizing the same technologies but would be based on a transient test cycle. New requirements for evaporative emissions and engine diagnostics would also start in 2007.

For recreational vehicles, the EPA is proposing emission standards for snowmobiles separately from off-highway motorcycles and all-terrain vehicles. For snowmobiles, the EPA is proposing a first phase of standards for HC and CO emissions based on the use of clean carburetion or 2-stroke electronic fuel injection (EFI) technology, and a second phase of emission standards for snowmobiles that would involve significant use of direct fuel injection 2-stroke technology, as well as possible limited conversion to 4-stroke engines. For off highway motorcycles and all-terrain vehicles, the EPA is proposing standards that would result in a 50% reduction and is based mainly on moving these engines from 2-stroke to 4-stroke technology. In addition, the EPA is proposing a second phase of standards for all-terrain vehicles that would require some catalyst use.

The proposal covers new engines that are used in the United States, whether they are made domestically or imported.